The present invention relates to blow molding methods and apparatuses, and, more particularly, a blow molding method and apparatus for producing large, reinforced plastic parts.
Recently, there has been an increase in the demand and applications for large, molded plastic parts, specifically parts that are greater than about 2 lbs. in weight and having a total surface area of greater than about 400 sq. inches. As a result, some of these parts have become quite complex. One example of this can be seen in radiator supports for automobiles. Design engineers are now integrating many features into the radiator support to reduce tooling and manufacturing costs.
The usefulness of blow molding techniques for forming such parts has not been practical due to the structural characteristics of the plastic material conventionally used in blow molding techniques. That is, the ability to blow molding large complex parts is limited by the fact that the parts produced can be only so large or so thin before the parts lose their structural integrity and impact resistance.
Heretofore, in order to reinforce various large complex plastic parts, such parts would conventionally be reinforced by mineral fillers or glass fibers. However, such reinforcement cannot be used effectively in blow molding operations, because the glass fibers limit parison expansion characteristics and also have a deleterious effect on the blow molding assembly itself. Furthermore, such reinforcement has a deteriorating effect on impact resistance of the part.